Pump cylinder



June 6, 1961 J c, FUNK ET A 2,986,886

PUMP CYLINDER Filed Nov. 15, 1958 M llli INVENTORS' Joseph C. Funk d By Howard C. Funk ATTORNEY GM States Patent 2,986,886 PUMP CYLINDER Joseph C. Funk and Howard C. Funk, both of 1211 W. 12th St, Coifeyville, Kans. Filed Nov. 13, 1958, Ser. No. 773,701

4 Claims. (Cl. 60-54.6)

This invention relates to improvements in pump cylinders and more particularly, but not by way of limitation, to a two stage hydraulic master cylinder for actuation of a clutch, or the like.

The present invention contemplates a novel hydraulic pump cylinder particularly designed and constructed for actuation of a clutch member, such as shown in our copending application entitled Power Take-Off Assembly, Serial No. 765,359 filed October 6, 1958. The master cylinder is provided with a co-axial large and small bore piston whereby alternate conditions of large volume fluid flow at relatively low pressure, and small volume fluid flow with considerably higher pressure may be automatically provided. A pressure sensitive shifting valve is provided in cooperation with the dual range piston in order that the large volume fluid flow is shut oif at a predetermined pressure, and the small volume fluid flow is permitted to continue at a considerably higher pressure, thus permitting a short travel uniform load actuating force for the piston. A hydraulic dampening piston is provided for retarding the action of the shifting piston when extremely rapid clutch motion is applied, thereby assuring the full performance cycle of the master cylinder at all times.

It is an important object of this invention to provide a novel hydraulic pump cylinder for actuation of a clutch member, or the like.

It is another object of this invention to provide a novel hydraulic pump cylinder having a dual range piston member whereby a large volume fluid flow is supplied at low pressure, and a small volume fluid flow is supplied at a higher pressure.

Another object of this invention is to provide a novel hydraulic cylinder whereby the fluid flow is automatically changed from large volume at low pressure to a small volume at a higher pressure at a predetermined pressure within the cylinder. H It is still another object of this invention to provide a novel hydraulic cylinder whereby the fluid flow is automatically shifted from small volume at a high pressure to a large volume at a lower pressure.

Still another object of this invention is to provide a novel hydraulic cylinder so designed and constructed to permit ashort travel uniform load actuating force for the piston.

.A further object of this invention is to provide a hydraulic cylinder which is simple and eflicient in operation and economical and durable in construction.

Other objects and advantages of the invention will be evident from the following detailed description, read in conjunction with the accompanying drawings, which illustrate our invention.

In the drawing:

The figure is a sectional elevational view of a master cylinder embodying the invention.

Referring to the drawings in detail, reference character refers in general to a hydraulic pump cylinder comprising a substantially cylindrical housing 12 having a reduced lower neck portion 14. An upper housing 16 having a substantially centrally disposed downwardly extending sleeve 18 is secured to the housing 12 oppositely disposed from the reduced neck 14 in any well known manner (not shown). A central bore 20 extends longitu'dinally through the neck portion 14 in substantial axial ice alignment with the sleeve 18 for receiving a reciprocal piston, generally indicated at 22, therein. An annular chamber 24 is provided in the housing 12. around the piston 22 for a purpose as will be hereinafter set forth. An oil or fluid reservoir chamber 26 is provided in the upper housing 16 around the sleeve 18.

The piston 22 is provided with a central bore 28 extending longitudinally upward therein and in communication with the bore 20. A suitable annular sealing member 30 is provided in the bore 20 around the outer periphery of the piston 22 for precluding leakage of fluid therebetween. A smaller central bore 32 extends longitudinally through the piston 22 from the bore 28 and throughout the length of the piston. A plurality of radially extending bores or passageways 34 are provided in the piston 22 above the larger bore 28 to provide com-j munication between the smaller bore 32 and the chamber 24 for a purpose as will be hereinafter set forth.

The piston 22 is enlarged toprovide a piston head 36 spaced above the passageways 34. The piston head 36 is integral with the piston 22, thereby providing a dual range piston having co-axial acting surfaces as will be hereinafter set forth. The piston head 36- slidably en-' gages the periphery of the chamber 24 as clearly shown in the drawings. A suitable annular sealing ring member 38 is provided on the outer periphery of the piston head 36 and adjacent the side walls of the chamber 24 to preclude leakage of fluid therebetween. A centrally disposed recess 40 is provided in the piston head 36 on the upper surface thereof for receiving a plunger 42 therein. The plunger 42 is slidably disposed in the sleeve 18 and extends longitudinally therethrough.

The plunger 42 is provided with a central bore or recess portion 44 adjacent the piston head 36 for a purpose as will be hereinafter set forth. A plurality of radially extending bores or passageways 46 extend from the recess 44 to provide communication with the chamber 26. An outwardly extending circumferential shoulder 48 is provided on the outer periphery of the plunger 42 for abutment with the sleeve 18 in order to limit the upward movement of the plunger 42 therein. A suitable passageway 50 may be provided in the sleeve 18 in order to direct fluid from the chamber 26 to the outer periphery of the plunger 42 for lubrication thereof upon reciprocation within the sleeve 18. An annular sealing ring member 52 is provided around the outer periphery of the plunger 42 above the passageway 50 for precludingtleakage of fluid between the plunger 42 and the upper housing 16-. A suitable recess 54 is provided in the upper end of the plunger 42 for receiving a pedal connection strut 56 whereby depression of a pedal (not shown) will move the plunger 42 downwardly within the sleeve 18, as will be hereinafter set forth.

A threaded inlet port 58 is provided in the upper housing 16 in order to provide access to the chamber 26. A suitable threaded insert member or plug 60 is preferably provided for the inlet portion 58 for closure thereof when it is not desirable to provide access to the chamber 26.. p

A suitable cover member 62 having a central bore 64 therein is secured to the lowermost end 66 of the housing 12 by suitable bolts 68, or the like. The bore 64 is in communication with the bore 20, and provides an outlet port therefor. A helical spring 78 is disposed within the bore 20 and extends upwardly in the bore 28' of the piston 22. One end of the spring 70 is anchored on the cover member 62, and the opposite end thereof is anchored on the upper shoulder 71 of the bore 28, whereby the spring 70 constantly urges the piston 22 ina direction toward the plunger 42.

A pressure sensitive shifting valve 72 is slidably disposed within the bore 32 of the piston 22 and extends longitudinally therethrough. A lower ring member 74 is suitably secured to the outer periphery of the valve 72 below the shoulder 71 of the piston 22 to provide a stop member for limiting the upward travel of the valve 72 within the bore 32. A suitable sealing ring member 76 is provided on the outer periphery of the valve 72 adjacent the stop member 74 for sealing against the shoulder 71 in the uppermost position (not shown) for the valve 72. A second ring member 78 is secured to the outer periphery of the valve 72 and spaced from the first ring 74 in order to contact the recess 40 for limiting the downward travel of the valve 72. A suitable sealing ring member 80 is provided on the outer periphery of the valve 72 and adjacent the second stop member 78 for sealing between the valve 72 and the piston. head 36 in the lowermost position of the valve 72, as shown in the drawings.

The outer periphery of the valve 72 is fluted to provide at least one longitudinal passageway 82 thereon. An annular groove 84 is provided on the outer periphery of the valve 72 and is preferably disposed substantially half way between the upper and lower stop members 78 and 74, respectively. A lower annular groove 86 is provided on the outer periphery of the valve 72- in the proximity of the lower stop member 74, and an upper annular groove 88 is provided on the valve 72 in the proximity of the upper stop member 78 for a purpose as will be hereinafter set forth.

A central bore 90 extends longitudinally downward within the valve 72 for slidably receiving a dampening piston 92 therein. A suitable helical spring 94 is disposed within the bore 90 below the dampening piston 92 for constantly urging the piston 92 upwardly and into contact with the recess 44 of the plunger 42, as clearly shown in the drawings.

A recharging valve stem 96 extends through an aperture 98 provided in the piston head 36. An outwardly extending circumferential flange 100 is provided on the lowermost end of the valve stem 96 for limiting the upward travel of the valve stem in the aperture 98. A second circumferential flange 102 is provided at the uppermost end of the valve stem 96 for limiting the downward travel thereof. Suitable sealing ring members, such as shown at 104 may be provided on the valve stem 96 for sealing the valve in a closed position, as will be hereinafter set forth. A helical spring 106 is disposed around the stem 96 above the piston head 36 and anchored to the upper flange 102 for constantly urging the valve stem 96 upwardly. An outwardly extending circumferential shoulder 108 is provided on the sleeve 18 for contacting the upper end of the valve stem 96 in order to move the valve stem 96 downwardly against the action of the spring 106 for opening of the recharging valve, as will be hereinafter set forth. A longitudinal passageway 110 is provided on the outer periphery of the valve stem 96 in order to provide communication between the chambers 24 and 26 in an open position of the valve 96.

Operation The chamber 24 is normally filled with a suitable fluid, such as oil, or the like (not shown), but not limited thereto. A reservoir or supply of the fluid is also retained in the chamber 26 for supplying or recharging the chamber 24 during the operation of the master or pump cylinder 10. The plunger 42 is normally in a raised position, as shown in the drawings, with the shoulder 48 in abutment with the sleeve 18 when the clutch pedal (not shown) carried by the pedal connection strut 56.is not depressed. It will be apparent that the piston 22 is constantly urged upwardly by the spring '70, and the contact between the piston head 36 and the plunger 42 maintains the plunger in the upper position when the, pedal is not depressed. p 7

The-weight of the pressure sensitive valve 72 in combination with the action of the helical spring 94 maintains the valve 72 in the lowermost position with respect to the piston 22, as shown in the drawings, when the plunger 42 is in the uppermost position adjacent the sleeve 18. With the valve 72 in this position, the central annular groove 84 thereof will be disposed in alignment with the radial ports 34 of the piston 22, thereby providing communication between the chamber 24 and the longitudinal passageway 82 of the valve 72. The lower flange 74 and sealing member 76 of the valve 72 are not in contact with the shoulder 71 of the piston, thereby permitting the fluid from the chamber 24 to flow downwardly through the passageway 82 and into the communicating bores 28 and 20. The outlet port 64- is normally in communication with the clutch member (not shown) being actuated by the cylinder =10 by means of suitable conduit members (not shown), or the like. Thus, the fluid in the bore 20 may flow through the outlet 64 and into contact with the clutch to be actuated. It will be apparent, however, that there is no pressure acting on the fluid when the clutchpedal is not depressed, thus there is no actuation of the, clutch member.

When it is desired to disengage the clutch member for any reason, the clutch pedal may be depressed in any well known manner (not shown), such as by use of the foot or hand. Depression of the clutch pedal simultaneously moves the connection strut 56 downward with respect to the cylinder 10. Thus, the plungerv 42 is moved downwardly within the sleeve 18 and moves the piston head 36 and piston 22 downwardly simultaneously therewith. The relatively large area of the piston head 36 acting on the fluid within the chamber 24 provides for a relatively large volumeof oil flow at a relatively low pressure to be forced through the radial ports 34 and downwardly into the bore 20 for discharge through the outlet 64. The fluid forced. through the outlet 64 is normally directed into contact with a hydraulically actuated clutch member (not shown) for a disengagement of the clutch.

A continued downward movement of the piston head 36 and piston 22 will continue the flow of fluid through the outlet 64. When the fluid begins to backup inthe bores 20 and 28 whereby the fluid pressure acting on the valve 72 becomes greater than the pressure of the spring 94 and overcomes the weight of, the valve 72, the valve 72 will be moved upwardly with respect to the piston 22. It will be apparent that the dampening plunger 92 will retard the upward movementof the valve 72 to compensate for rapid clutch pedal actuation. When the valve 72,-moves to the full upward, position within the piston 22, the lower flange 74 and sealing member 76 will seal against the shoulder 71 to preclude the downward flow of the fluid through thepassageway 82, and the upper flange 78 will be simultaneously moved away from the recess 40. Thus, the flow of the fluid will be diverted upwardly through the passageway 82 and to the upper annular groove 88 for discharge into the bore 44. The fluid will flow outwardly throughv the radial ports 46 and into the reservoir chamber 26.

It will be apparent that the lowered position for the plunger 42 will move the valvestem 96 downwardly and away from the flange 108 of the sleeve 18. .Thus, the spring 106 will maintain the valve stem 96 in anupper position with respect to thepistonthead 36 for maintaining the valve 96 in a closed position and preclude the flow of fluid from thechamber 26 to the chamber-'24 therethrough.

As the pressure sensitive valve 72 is closing, it will be apparent that the volume of fluid entering the bore 28 will diminish. In addition,.the area of the: annular shoulder 71 will be actingv on, the fluid for-moving: the fluidtdownwardlya and out the. port64. The area of the shoulder 71 is'substantially less-thamthe area of. the pist'on head. 36. Thus,- the, pressurev of. the. fluid willbe greatly increased, although the volume'thereof is. substantially reduced. Thus, a smaller fluid volume at a higher pressure is directed to the hydraulic clutch actuating member. This provides for a shorttravel uniform load of the plunger 42 and the clutch pedal actuating the plunger.

When the clutch pedal is released, the spring 70 will urge the piston 22 and the piston head 36 upwardly. The plunger 42 will be moved upwardly simultaneously with the piston head 36 until the flange 48 is in abutment with the sleeve 18, as shown in the drawings. In this position, the flange 108 of the sleeve 18 strikes the upper end of the valve stem 96 and moves the stem 96 downwardly with respect to the piston head 36 for an opening of the valve 96. Thus, the passageway 110 is open to both the chambers 24 and 26 and permits the fluid to flow downwardly by gravity into the chamber 24 for a recharging thereof. It will be apparent that the fluid present in the bores 20 and 28 will flow upwardly through the passageway 82 of the valve 72 in order to relieve the pressure in the bores as the piston 22 is returned to the normal position therefor.

By way of summary, depression of the clutch pedal will move the plunger 42 downwardly whereby the piston head 36 will force the fluid in the chamber 24 downwardly through the passageway 82 for discharge through the out let port 64. The relatively large area of the piston head 36 will provide for a relatively large volume of oil flow at a relatively small pressure. When the pressure in the bores 20 and 28 reaches a predetermined level, the pressure sensitive valve 72 is actuated to shut off the flow of fluid from the chamber 24 to the outlet 64. Thus, the volume of fluid moving through the outlet port is reduced. However, the area of the shoulder 71 acting on the smaller volume of fluid is substantially smaller than the area of the piston head 36, thereby providing for a higher pressure for the smaller volume of fluid. Thus, a short travel uniform load actuating force is provided for the cylinder 10.

From the foregoing, it will be apparent that the present invention provides a novel pump cylinder having a coaxial large and small bore piston to provide alternate conditions of large volume oil flow at low pressure and small volume oil flow at a higher pressure. Thus, a short travel uniform load actuating force is provided for the cylinder. The novel master cylinder is simple and efficient in operation and economical and durable in construction.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

We claim:

1. A pump cylinder comprising a housing, a reduced neck portion provided on the housing for receiving a piston member therein, an enlarged chamber in the housing above the reduced portion, an enlarged piston head integral with the piston and disposed in the enlarged chamber, a plunger reciprocally disposed in the housing above the piston head for moving the piston head and piston downwardly within the housing, spring means cooperating with the piston for constantly urging the piston and piston head upwardly within the housing, said plunger cooperating with the housing to determine the upward travel of the piston head, a fluid reservoir chamber provided in the housing above the enlarged piston head, a pressure sensitive valve means carried by the piston and reciprocal therein for automatically shifting the action of the integral piston head and piston from the enlarged piston head to the piston to provide alternate conditions of large volume of fluid flow at a low pressure and a small volume of fluid flow at a higher pressure, and a valve carried by the piston head for cooperation with an abutment of the housing to provide a fluid recharging of the enlarged chamber from the fluid reservoir, said valve movable to a closed position upon application of pressure to the pis-- ton head by the plunger to preclude the passage of fluid therethrough.

2. A pump cylinder comprising a housing, a reduced neck portion provided on the housing for receiving a piston member therein, an enlarged chamber in the housing above the reduced portion, an enlarged piston head integral with the piston and disposed in the enlarged chamber, a plunger reciprocally disposed in the housing above the piston head for moving the piston head and piston down- Wardly within the housing, spring means cooperating with the piston for constantly urging the piston and piston head upwardly within the housing, said plunger cooperating with the housing to determine the upward movement of the piston head, a fluid reservoir chamber provided in the housing above the enlarged piston head, pressure sensitive valve means carried by the piston and reciprocal therein for automatically shifting the action of the piston from the enlarged smaller portion of the piston head to the piston to provide alternate conditions of large volume fluid flow at low pressure and small volume fluid flow at a higher pressure, and valve means carried by the piston head for cooperation with the housing to provide a fluid recharging of the enlarged chamber from the fluid reservoir, said valve means movable to a closed position upon application of pressure to the piston head by the plunger to preclude the passage of fluid therethrough.

3. A pump cylinder comprising a housing, a reduced neck portion provided on the housing for receiving a piston member therein, an enlarged chamber in the housing above the reduced portion, a piston provided with coaxial enlarged and smaller portions, said enlarged piston portion disposed in the enlarged housing chamber and the smaller piston portion disposed in the reduced neck portion of the housing, a plunger reciprocally disposed in the housing above the piston for moving the piston downwardly within the housing, spring means cooperating with the piston for constantly urging the piston upwardly within the housing, a fluid reservoir chamber provided in the housing above the enlarged portion of the piston, a pressure sensitive valve carried by the piston and reciprocal therein between two positions, said valve movable to a first position to allow fluid from the enlarged chamber to flow into the reduced neck chamber so as to provide a large volume of fluid fiow at a low pressure, said valve movable to a second position to permit the fluid in the fluid in the enlarged chamber to flow into the reservoir chamber thereby allowing the small piston to provide a small volume of fluid flow at a high pressure, dampening means carried by the pressure sensitive valve and reciprocal therein to slow the movement of the pressure sensitive valve from the first to the second position, and a valve carried by the piston head for cooperation with an abutment of the housing to provide a fluid recharging of the enlarged chamber from the fluid reservoir.

4. A pump cylinder comprising a housing, a reduced neck portion provided on the housing for receiving a piston member therein, an enlarged chamber in the housing above the reduced portion, a piston provided With co-axial enlarged and smaller portions, said enlarged piston portion disposed in the enlarged housing chamber and the smaller piston portion disposed in the reduced neck portion of the housing, a plunger reciprocally disposed in the housing above the piston for moving the piston downwardly within the housing, spring means disposed Within the reduced housing portion and cooperating with the piston for constantly urging the piston upwardly within the housing, a fluid reservoir chamber provided in the housing above the enlarged portion of the piston, a pressure sensitive valve carried by the piston and reciprocal therein between two positions, said valve being provided with a longitudinally extending passageway along its outer periphery, said valve movable to a first position to allow fiuid from the enlarged chamber to flow downwardly through its longitudinal passageway into the reduced neck chamber so as to provide a large volume of Mid flow' at a low pressure, said valve movable to a second position topermit the fluid in the enlarged chamber to flow upwardly in the longitudinal passageway into the reservoir chamber thereby allowing the small piston portion to portion to provide a small volume of fluid flow at a high pressure, a dampening piston carried by the pressure sensitive valve and reciprocal therein to slow the movement of the pressure sensitive valve from the first to the second position, and a valve carried by theenlarged piston portion for cooperation with an abutment of the housing to provide afiuid recharging of the enlarged chamber from.

the fluid reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 

